| Summary: | 碩士 === 中原大學 === 土木工程研究所 === 94 === ABSTRACT
In this research, the least-squares finite element method (LSFEM) is employed to study the influence of asymmetric stenosis on the flow fields and mass transfer in the blood vessel. There are three kinds of asymmetric arterial stenosis (53.18% , 65.75% , 77.65%) established in the article. The changes of flow fields, shear stress, pressure drop, reversed flow regions and the variation of blood density on mass transfer in the reversed flow regions distal to the arterial stenosis are carefully examined.
In this article, the Reynolds number is between 100-1000 in the flow fields. Both the flow field and pressure drop are in according with the results of early researcher’s studies. In three kinds of different arterial stenosis models, the maximum shear stress occurs in the throat of the arterial stenosis. The low shear stresses exist in the reversed flow regions distal to the arterial stenosis. At the same cross-section of the arterial, the ratio between the peak shear stress at the wall of arterial stenosis(53.81%) and that in the normal wall is 2.06: 1; and this result is irrelevant with different Reynolds numbers. As the increase of the arterial stenosis, the peak shear stress ratio between the normal and abnormal walls is decreased.
In the mass transfer, the maximum oxygen mass transfer occurs proximal to the stenosis; and it is the same place that the peak wall shear stress exists. Concentration distribution distal to the arterial stenosis will form into two streams, the normal oxygen concentration stream is along the normal artery wall, and the low oxygen concentration is formed in the reverse region distal to the arterial stenosis. It is clear that the mass transfer of oxygen can be used to see the changes and distributions in arterial stenosis of the blood vessel.
Based on the numerical simulation, this research can be concluded that this numerical model can simulate the whole complicate flow domain in good agreement with the available simulation results and the observed experiments.
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